I still have light brown discharge on my underwear...should i worry or not? 9 weeks pregnant po.

Naultrasound na po ako on my 6weeks of pregnancy, bngyan akong duphaston taken twice a day..for 1 week...wala namn nakitang bad signs sa loob ng tyan ko, pero bakit may light brown pa rin na nalabas? #2ndbaby D ako ganito nung first baby ko.